Article of furniture for sitting

ABSTRACT

An article of furniture for sitting has a seat element, a back, a support frame having a support and a mechanical structure for transmitting a movement, which connects the support in a rear seat region with the seat element, at least one spring element displacing the seat element in an abutment or return position, the spring element being formed as a front mounting for the seat element and supported on the support which is stationary, the spring element in addition to known restoring function also determining a guidance of the seat element in its front region.

BACKGROUND OF THE INVENTION

[0001] The present invention relates generally to articles of furniture,and in particular to an article of furniture for sitting.

[0002] The German patent document DE 196 07 136 A1 discloses a chairwith a so-called synchronizing mechanical system. The synchronizingmechanical system is used for backing in the chair and, in addition to atilting movement of the back rearwardly, provides the lowering of theseat element in a rear seating region which is close to the back andlifting the seating element in a front seat region which is remove fromthe back. Therefore the sitting person during backing has the feeling ofsliding into the chair and not the filling of sliding from the chair.With a spring element which acts on a suspension arranged in the frontseat region on the seat element, the seat element is adjusted in aninitial position. Against the force which must hold the seat element inthe back in the initial position, the sitting person must apply a forceagainst the back and against the spring element for reaching a backtilting of the chair or a change in angular position of the seatelement. A movement of the seat element is possible substantially onlyby loading or unloading of the back. The front region of the seatelement is in a fixed predetermined position when the back is unloaded.The movements of the seat element are provided by levers and/or guides.It is believed to be advisable to further improve the existing chairs.

SUMMARY OF THE INVENTION

[0003] Accordingly, it is an object of present invention to provide anarticle of furniture for sitting which avoids the disadvantages of theprior art.

[0004] More particularly, it is an object of the present invention toprovide an article of furniture for sitting which in addition to thecomfort provided by the synchronizing mechanical system provides furthercomfort properties in the region of the seat element and a simplifiedconstruction of the synchronizing mechanical system.

[0005] In keeping with these objects and with others which will becomeapparent hereinafter, one feature of the present invention resides,briefly stated, in an article of furniture for sitting, comprising aseat element; a back; a support frame having a support and a mechanicalmeans for transmitting a movement, which connects said support in a rearseat region with said seat element; at least one spring elementdisplacing said seat element in an abutment or return position, saidspring element being formed as a front mounting means for said seatelement and supported on said support which is stationary, said springelement in addition to known restoring function also determining aguidance of said seat element in its front region.

[0006] The article of furniture for sitting in accordance with thepresent invention has front mounting means for the seat element which isformed as a spring element supported on a stationary support part,wherein the spring element takes over, in addition to the knownrestoring function, also the guidance of the seat element in its frontregion. Thereby the components which are required for holding andguiding the spring element as disclosed in the German patent document DE196 07 136 A1 in the chair with a synchronizing mechanical system are nolonger necessary to guide the force of the spring and to control a partof the movement course of the seat element.

[0007] Furthermore such a double function or double functions of thespring increase the comfort or the suitability of the chair for personswith any size and any body weight. This results from the fact that theopening angle between the seat element and the back due to theconstruction of the inventive spring element is no longer determinablealone by the size of the force against the back and thereby theinclination of the chair. An increase of the opening angle between theseat element and the back which often is desired for heavier personswith a greater body volume can be adjusted now substantiallyautomatically in that the person with a greater body weight and agreater body volume applies a greater force to the spring element and incontrast to the known spring element in the German patent document DE196 07 136 A1 it has the freedom to deviate in a substantiallyperpendicular direction. Thereby the seat element is tilted forwardly orsinks in a forward region and obtains independently from the positionunloading of the back an increase opening angle between the back and theseat element. In addition to this comfort for the person with a greaterbody weight and a greater body volume, a further advantage is providedfor a person which sits in the front region of the seat element. Such asitting position is often assumed by persons who operate at a computer.In such a working position it has been found as advantageous when theseat surface is inclined slightly forwardly. This orientation of theseating means is also provided by the additional freedom of theinventive spring element. The person which is loaded in such a seatposition of the seat element presses with a small body weight the centerof gravity of the body located in this position substantially over thefront edge of the seat element the spring element downwardly, so that itadjusts the desired inclination of the seat element forwardly. Thisposition of the seat element facilitates and favors a favorable bodyhold from the medical point of view, in which the pelvis of the sittingperson is tilted forwardly.

[0008] In accordance with another advantageous embodiment of theinvention, the spring element is formed as a leaf spring which extendsand is bent preferably in a seat direction. A leaf spring, in otherwords an individual leaf spring or a leaf spring pack satisfies therequirements of the spring element in an ideal fashion, since the bentleaf spring applies passing forces in the both required directions. Onthe one hand the leaf spring acts upwradly. Thereby the seat element islifted or held in the front region. On the other hand the leaf springacts forwardly in seat direction. Thereby the seat element is loadedwith a force forwardly and thereby acts for lowering of the rear seatregion. Thereby the leaf spring holds the seat element and with it alsothe back directly or indirectly connected to it, in a front abutment orat a storing position. A backing in the chair leads depending on theshape or bending of the leaf spring, in addition to a sinking of therear seat region, to a lifting of the front seat region or to aretention of the front seat region at a certain height.

[0009] An adjustability of the spring element allows the maintaining theseat element optimal to the requirements or desires of the sittingperson. In particular a small, light person can increase the openingangle between the seat means and the back without tilting back.Simultaneously through the adjustment of the force of the springelement, also the tilting ability or tilting conditions of the chair canbe influenced.

[0010] In accordance with another special embodiment of the invention,the spring force of the leaf spring can be varied by displacement of thespring abutment point and/or a change of the distance between theindividual spring sheets. These adjustments can be realized by anspecially simple and therefore cost-favorable adjusting mechanism.

[0011] Furthermore, it is advantageous when the spring element is formedas helical springs and/or rubber elements, and/or rubber-metallicelements, and/or hydraulic cushions and/or pneumatic cushions, or acombination of these elements. These spring elements provide anadaptation to different requirements and mounting possibilities.

[0012] It is especially advantageous when the invention is utilized in achair with a back, which is connected through a back support with themeans for movement transmission. With this arrangement a chaircompletely maintain a comfort, which goes beyond the comfort of thechair of the prior art.

[0013] It is further proposed to provide the chair with the inventivecomfort function in which the back is directly connected to the seatelement. Thereby a mechanically simple and cost-favorable chair isformed with a high comfort. In a transition region from the seat elementto the back, of an elastic chair an article of furniture for sitting isformed which despite its simple construction provides the comfort of theabove described chairs.

[0014] With the use of a seat element which is composed of a base plateand a support displaceably arranged on it, it is possible to adapt thechair in the sitting region optimally to the required supporting surfacefor the hip of the person sitting on the chair. Thereby the suitabilityof the chair for persons of different body sizes and body weights isincreased.

[0015] The novel features which are considered as characteristic for thepresent invention are set forth in particular in the appended claims.The invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a side view of office chair in accordance with a firstembodiment of the present invention in a forward abutment position;

[0017]FIG. 2 is a side view of the office chair shown in FIG. 1 in therear abutment position;

[0018]FIG. 3 is a plan view of the office chair in accordance with thepresent invention shown in FIG. 1;

[0019]FIG. 4 is a side view of an office chair in accordance with asecond embodiment of the present invention in a front abutment position;

[0020]FIG. 5 is a side view of the inventive office chair shown in FIG.4 in the rear abutment position;

[0021]FIG. 6 is a plan view of the inventive office chair of theembodiment of FIG. 4;

[0022]FIG. 7 is a side view of an office chair in accordance with athird embodiment of the present invention, in a front abutment position;

[0023]FIG. 8 is a side view of the inventive office chair of FIG. 7 inthe rear abutment position;

[0024]FIG. 9 is a plan view of the inventive office chair shown in FIG.7;

[0025]FIG. 10 is a side view of an office chair in accordance with afourth embodiment of the present invention in the front abutmentposition;

[0026]FIG. 11 is a side view of the inventive office chair of FIG. 10 inthe front abutment position;

[0027]FIG. 12 is a plan view of the inventive office chair of FIG. 10;

[0028]FIG. 13 is a side view of an office chair in accordance with afifth embodiment of the present invention in the front abutmentposition;

[0029]FIG. 14 is a side view of the inventive office chair of FIG. 18 inthe rear abutment position;

[0030]FIG. 15 is a plan view of the inventive office chair of FIG. 13;

[0031]FIG. 16 is a side view of an office chair in accordance with the asixth embodiment of the present invention in the forward abutmentposition;

[0032]FIG. 17 is a side view of the inventive office chair of FIG. 13and the rear abutment position; and

[0033]FIG. 18 is a plan view of the inventive office chair of FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034]FIG. 1 shows a side view of an article of furniture for sitting 1which is formed as an office chair 2. The office chair 2 substantiallyhas a rotary frame 3 with rollers 4, which is connected through an axle5 with a supporting part 6 in a vertically adjustable and rotatablemanner. It also has a seat element 7 mounted on the supporting part 6and a back 9 which is connected with support part 6 through a backsupport 8.

[0035] The support part 6 is composed of a rigid support 10 whichreceives the axle 5, means 11 for transmission of a movement which areformed as levers 12, and a front mounting means 14 which is formed as aspring element 15. The seat element 7 is composed of a support member 16and a base plate 17. The support member 16 is displaceable relative tothe base plate 17 in a seat direction A between a first position P and asecond position P′, and is arrestable. Due to such a displacement, thesupporting surface for the hip of a person who sits on the office chair2 is individually adujustable.

[0036] Forward flange means 19, 20 are arranged in a front seat region18 on the seat element 7 or on the base plate 17, and rear flange means22, 23, are arranged in a rear seat region 21 of the same, as shown inFIG. 3. The first flange means 19, 20 receive each a spring element 15,wherein the spring elements 15 are formed as leaf springs 24, 25. Theleaf springs 24, 25 act as springy jibs, so that the seat element 7 isrotatably hinged on their free ends through the front flange means 19,20.

[0037] In FIG. 1 the office chair 2 is shown in an upright or frontabutment position I, which it assumes in a condition in which it is notloaded with a person or in other words it is unloaded. In this frontabutment position I the spring element 15 lifts due to a verticallyacting force F_(z) in the arrow direction Z of the seat element 7 at aheight H. Furthermore, a horizontal force F_(x) of the spring element 15pulls the seat element 7 in arrow direction x to the position I shown inFIG. 1. The spring force acts through the rear flange means 22, 23 alsoon the lever 12 and the back support 8 which are connected to thesupport 10 turnably about an axis 26. Through the lever 12 a circularpath K is defined, over which an axle 27 connecting the rear flangemeans 22, 23 with the levers 12 or the back support 8 can move.

[0038] By loading of the office chair 2 with the force F_(s) by a personsitting on the office chair 2 the seat element 7 turns by the portion ofthe force F_(s) acting in the front seating region, substantiallyagainst the clockwise direction around the bearing point 27 until theportion of the force F_(s) is compensated by the force F_(z) of thespring element 15 acting opposite to it. The portion of the force F_(s)acting in the rear seat region is taken for the lever 12, the supportpart 10, the axle 5 and the rotary frame or a pulling force by thespring element 12 acts through the lever 12 which is compensated by thisforce component F_(s). Therefore depending on the acting forces F_(s)and F_(z) an inclined position of the seat element 7 results for examplein an inclined position 28 identified with a broken line. Thereby anopening angle a enclosed between the back 9 and the seat element 7 isincreased to an opening angle α′. A lowering of the seat element 7 canbe performed both by a person which has contact of his back against theback of the chair 9, which seats exclusively in the front of the seatregion 19. Such a person understandably provides a greater inclinedposition of the seat surface 7, when it sits exclusively in the frontseat region 18, since then van a greater part of the body weight acts onthe spring element 15.

[0039]FIG. 2 shows the office chair 2 of FIG. 1 in a rear abutmentposition 11. The office chair 2 in this position is held by a force.F_(R) originates from the sitting person and acting on the back 9. Theforce F_(R) is compensated by the force F_(x) of the spring element 15.Thereby the movement of the back 9 and the seat element 7 is limited bythe spring element 15. Substantially the force F_(R) is transmittedthrough the back support 8 and the seat element 7 as a pulling forcewith a spring element 15, while the axle 27 assumes the position shownin FIG. 2 by a turning on the circular path K from the position shown inFIG. 1. The force F_(R) activates thereby, via the synchronousmechanical system, or in other words the special connection of the back9 and the seat element 7, in addition to the turning of the back 9 in aclockwise direction, also a movement of the axle 27 in counterclockwisedirection over the circular path K which is originated by a rotation ofthe seat element in a clockwise direction around the axle 27. Thereby bythe synchronous mechanical system a typical sinking of the seat element7 is produced in the rear seat region 21, and a lifting of the seatelement 7 in the front seat region 18.

[0040] These movements produced by the synchronous mechanical system aresuperposed by a further movement which makes possible the unguidedspring element. The further movement results in that the sitting personacts with a force F_(S) on the seat surface 7, with a part of this forceapplied in the front seat region 18 compensated by the force F_(Z) ofthe spring element 15. Depending on the magnitudes of the acting forcesF_(Z) and F_(x) , a changeable opening angle which is changed relativeto the opening angle a of FIG. 2 is produced. Thereby the opening angleis not determined by the synchronous mechanical system alone, butsubstantially is a function of the forces F_(S) and F_(z).

[0041]FIG. 3 shows a plan view of the office chair 2 of FIG. 1, whereinthe illustration of the rotary frame and the rollers is dispensed with,however the other components located under the seat element 7 are shown.In the region of the back 9 this illustration is also simplified. Thesupport 10 is U-shaped and receives the spring element 15 at the freelegs 29, 30. The back support 8 is arranged in the rear flange means 22,23, and the lever 20 is formed as a fork 31.

[0042] FIGS. 4-6 show a second embodiment of the office chair 32. Incontrast to the embodiments of FIGS. 1-3, the office chair has means 33for adjusting the spring force of the spring element 15. As means 33 foradjusting the spring force, a tensioning device 34 is proposed. Thetensioning device 34 has a hand wheel 35 which actuates the not showntensioning screw for changing the distance between individual springleaves 36 on the spring element 15. A smaller distance between thespring leave 36 provides a greater tensioning force of the springelement 15. Furthermore, the office chair 32 shown in FIGS. 4-6 is alsodifferent from the office chair of FIGS. 1-3 in that, for the springingof a seat element 7 only one spring element 15 is utilized. Thereby aparticularly narrow construction of the office chair 32 is possible.

[0043] FIGS. 7-9 show a third office chair 37. In contrast to the officechair 32 shown in FIGS. 4-6, a spring element 15 is formed as a rubberelement 38 or a rubber metal 39. As a rubber metal, a synthetic plasticelement, in particular a rubber element provided between two metalplates is utilized. The spring element 15 has spring properties actingin x and z directions. A springing in a transverse direction y isprovided by the mechanical connection of a seat element 7 through alever 12 to a support 10. When the office chair 37 shown in FIG. 8 is ina rear abutment position II, then the spring element 15 is subjected toa shearing load. Its acts in all positions in which the office chair 37assumes a position in which a back 9 is inclined relative to theposition shown in FIGS. 7.

[0044] FIGS. 10-12 show an office chair 40 in accordance with a fourthembodiment of the present invention which is substantially similar tothe third office chair of FIGS. 7-9. In this office chair the springelement 15 is formed as a helical spring 41. As for the operation, herethe description of the office chair of FIGS. 7-9 is applicable since thehelical spring element 41 is comparable with the rubber element 38 orthe rubber metal 39.

[0045] An office chair 42 in accordance with a fifth embodiment of thepresent invention is shown in FIGS. 13-15. In contrast to the officechair shown in FIGS. 1-12, the office chair 42 has a seat shell 43. Theseat shell 43 is composed of a back 9 which is connected of one piecewith a seat element 7. The seat shell 43 in a transition region 44 iselastic or springy. A partial function of the synchronous mechanicalsystem namely the increase of an opening angle a between the back 9 andthe seat 7 is taken in the office chair 42 by the flexible or elastictransition region 44, which activates a back springing of the back 9 independence on the force F_(R) acting on it and applied by a personsitting on the office chair 42. Similarly to the office chairs shown inFIGS. 1-12 the force F_(R) , depending on the counter force F_(X)produced by a spring element 15, activates sinking of the seat shell 43in the rear seat region 21 and lifting the seat shell 43 in a front seatregion 18. A weight force F_(S) applied by a sitting person or itsportion acting in the front seat region 18 leads to a lowering of theseat element contrary the clockwise direction. In the office chair 42 itprovides driving the back when the opening angle a of the seat shell 43is not increased by an increasing force F_(R) acting on the back 9.

[0046] A sixth office chair 45 is shown in FIGS. 16-18. The office chair45 has, as the office chair 42 shown in FIGS. 13-15, a seat shell 43which is composed of a seat element 7 and a back 9 springy connected ina transition region. In contrast to the office chairs shown in FIGS.1-15, in the office chair 45 the rotatably connected lever which servesas means 11 for transmission of a movement, is replaced by guides 13.The guides 13 are formed as elongated openings 46 provided in beams 47.The beams 47 are fixedly connected with a support 10. Rear flange means22, 23, which are fixedly connected with the seat shell 43 are supportedin a longitudinal openings 46 through a throughgoing axle 27.

[0047] The invention is not limited to the shown and describedembodiments. It includes many further modifications of the inventionwithin the range of the protection rendered by the claims. Inparticular, it is possible to provide the inventive arrangement of aspring element also on furniture articles for sitting which do not havea rotary frame, but instead have standing legs or standing feet and/orare fixedly mounted.

[0048] It will be understood that each of the elements described above,or two or more together, may also find a useful application in othertypes of constructions differing from the types described above.

[0049] While the invention has been illustrated and described asembodied in sifting article of furniture, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit of thepresent invention.

[0050] Without further analysis, the foregoing will so fully reveal thegist of the present invention that others can, by applying currentknowledge, readily adapt it for various applications without omittingfeatures that, from the standpoint of prior art, fairly constituteessential characteristics of the generic or specific aspects of thisinvention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.
 1. An article of furniture forsitting, comprising a seat element; a back; a support frame having asupport and a mechanical means for transmitting a movement, whichconnects said support in a rear seat region with said seat element; atleast one spring element displacing said seat element in an abutment orreturn position, said spring element being formed as a front mountingmeans for said seat element and supported on said support which isstationary, said spring element in addition to known restoring functionalso determining a guidance of said seat element in its front region. 2.A sitting article of furniture as defined in claim 1, wherein saidmechanical means for transmitting a movement include lever means.
 3. Asitting article of furniture as defined in claim 1, wherein saidmechanical means for transmitting a movement include guide means.
 4. Asitting article of furniture as defined in claim 1, wherein said springelement is formed as a leaf spring which is tensioned at one side.
 5. Asitting article of furniture as defined in claim 4, wherein said leafspring extends in a seat direction.
 6. A sitting article of furniture asdefined in claim 1, wherein said spring element has an adjustable springforce.
 7. A sitting article of furniture as defined in claim 3, whereinsaid spring has a support point, said leaf spring being adjustable bydisplacing said support point.
 8. A sitting article of furniture asdefined in claim 3, wherein said leaf spring has a spring force which isadjustable by changing a distance between individual leaves of said leafspring.
 9. A sitting article of furniture as defined in claim 1, whereinsaid spring element is formed as a helical spring.
 10. A sitting articleof furniture as defined in claim 1, wherein said spring element isformed as a rubber element.
 11. A sitting article of furniture asdefined in claim 1, wherein said spring element is formed as a metalrubber element.
 12. A sitting article of furniture as defined in claim1, wherein said spring element is formed as a hydraulic cushion.
 13. Asitting article of furniture as defined in claim 1, wherein said springelement is formed as a pneumatic cushion.
 14. A sitting article offurniture as defined in claim 1; and further comprising a back supportwhich is connected with said means for transmitting movement, said backbeing mounted on said back support.
 15. A sitting article of furnitureas defined in claim 1, wherein said back is mounted on said seatelement; and further comprising a transition region provided betweensaid back and said seat element.
 16. A sitting article of furniture asdefined in claim 15, wherein said transition region is springy.
 17. Asitting article of furniture as defined in claim 15, wherein saidtransition region is elastic.
 18. A sitting article of furniture asdefined in claim 15, wherein said back and said seat element togetherform a seat shell.
 19. A sitting article of furniture as defined inclaim 1, wherein said seat element has a rest member and a base platewhich are displaceable relative to one another.